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<meta name="description" content="Drag and drop items between nodes."/> 
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<title>Dragging Fields Between Records</title>
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          <h1 class="mb-0 p-1 ">GoJS</h1>
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    <!-- Start of GoJS sample code -->
    
    <script src="../release/go.js"></script>
    <div class="p-4 w-full">
    <script id="code">
    // Custom DraggingTool for dragging fields instead of whole Parts.
    // FieldDraggingTool.fieldTemplate needs to be set to a template of the field that you want shown while dragging.
    function FieldDraggingTool() {
      go.DraggingTool.call(this);
      this.fieldTemplate = null;  // THIS NEEDS TO BE SET before a drag starts
      this.temporaryPart = null;
    }
    go.Diagram.inherit(FieldDraggingTool, go.DraggingTool);

    // override this method
    FieldDraggingTool.prototype.findDraggablePart = function() {
      var diagram = this.diagram;
      var obj = diagram.findObjectAt(diagram.lastInput.documentPoint);
      while (obj !== null && obj.type !== go.Panel.TableRow) obj = obj.panel;
      if (obj !== null && obj.type === go.Panel.TableRow &&
        this.fieldTemplate !== null && this.temporaryPart === null) {
        var tempPart =
          go.GraphObject.make(go.Node, "Table",
            { layerName: "Tool", locationSpot: go.Spot.Center },
            this.fieldTemplate.copy());  // copy the template!
        this.temporaryPart = tempPart;
        // assume OBJ is now a Panel representing a field, bound to field data
        // update the temporary Part via data binding
        tempPart.location = diagram.lastInput.documentPoint;  // need to set location explicitly
        diagram.add(tempPart);  // add to Diagram before setting data
        tempPart.data = obj.data;  // bind to the same field data as being dragged
        return tempPart;
      }
      return go.DraggingTool.prototype.findDraggablePart.call(this);
    };

    FieldDraggingTool.prototype.doActivate = function() {
      if (this.temporaryPart === null) return go.DraggingTool.prototype.doActivate.call(this);
      var diagram = this.diagram;
      this.standardMouseSelect();
      this.isActive = true;
      // instead of the usual result of computeEffectiveCollection, just use the temporaryPart alone
      var map = new go.Map(/*go.Part, go.DraggingInfo*/);
      map.set(this.temporaryPart, new go.DraggingInfo(diagram.lastInput.documentPoint.copy()));
      this.draggedParts = map;
      this.startTransaction("Drag Field");
      diagram.isMouseCaptured = true;
    };

    FieldDraggingTool.prototype.doDeactivate = function() {
      if (this.temporaryPart === null) return go.DraggingTool.prototype.doDeactivate.call(this);
      var diagram = this.diagram;
      // make sure the temporary Part is no longer in the Diagram
      diagram.remove(this.temporaryPart);
      this.temporaryPart = null;
      // now do all the standard deactivation cleanup,
      // including setting isActive = false, clearing out draggedParts, calling stopTransaction(),
      // and setting diagram.isMouseCaptured = false
      go.DraggingTool.prototype.doDeactivate.call(this);
    };

    FieldDraggingTool.prototype.doMouseMove = function() {
      if (!this.isActive) return;
      if (this.temporaryPart === null) return go.DraggingTool.prototype.doMouseMove.call(this);
      var diagram = this.diagram;
      // just move the temporaryPart (in draggedParts), without regard to moving or copying permissions of the Node
      var offset = diagram.lastInput.documentPoint.copy().subtract(diagram.firstInput.documentPoint);
      this.moveParts(this.draggedParts, offset, false);
    };

    FieldDraggingTool.prototype.doMouseUp = function() {
      if (!this.isActive) return;
      if (this.temporaryPart === null) return go.DraggingTool.prototype.doMouseUp.call(this);
      var diagram = this.diagram;
      var data = this.temporaryPart.data;
      var dest = diagram.findPartAt(diagram.lastInput.documentPoint, false);
      if (dest !== null && dest.data && dest.data.fields) {
        var panel = dest.findObject("TABLE");
        var idx = panel.findRowForLocalY(panel.getLocalPoint(diagram.lastInput.documentPoint).y);
        diagram.model.insertArrayItem(dest.data.fields, idx + 1,
          { name: data.name, info: data.info, color: data.color, figure: data.figure });
      }
      var src = this.currentPart;
      // whether or not there was a destination node, delete the original field
      if (!(diagram.lastInput.control || diagram.lastInput.meta)) {
        var sidx = src.data.fields.indexOf(data);
        if (sidx >= 0) {
          diagram.model.removeArrayItem(src.data.fields, sidx);
        }
      }
      this.transactionResult = "Inserted Field";
      this.stopTool();
    };
    // end of FieldDraggingTool


    function init() {
      var $ = go.GraphObject.make;  // for conciseness in defining templates

      myDiagram =
        $(go.Diagram, "myDiagramDiv",
          {
            validCycle: go.Diagram.CycleNotDirected,  // don't allow loops
            draggingTool: $(FieldDraggingTool),  // use custom DraggingTool
            // automatically update the model that is shown on this page
            "ModelChanged": function(e) { if (e.isTransactionFinished) showModel(); },
            "undoManager.isEnabled": true
          });

      // This template is a Panel that is used to represent each item in a Panel.itemArray.
      // The Panel is data bound to the item object.
      // This template needs to be used by the FieldDraggingTool as well as the Diagram.nodeTemplate.
      var fieldTemplate =
        $(go.Panel, "TableRow",  // this Panel is a row in the containing Table
          new go.Binding("portId", "name"),  // this Panel is a "port"
          {
            background: "transparent",  // so this port's background can be picked by the mouse
            fromSpot: go.Spot.Right,  // links only go from the right side to the left side
            toSpot: go.Spot.Left
          },  // allow drawing links from or to this port
          $(go.Shape,
            { width: 12, height: 12, column: 0, strokeWidth: 2, margin: 4 },
            new go.Binding("figure", "figure"),
            new go.Binding("fill", "color")),
          $(go.TextBlock,
            { margin: new go.Margin(0, 2), column: 1, font: "bold 13px sans-serif" },
            new go.Binding("text", "name")),
          $(go.TextBlock,
            { margin: new go.Margin(0, 2), column: 2, font: "13px sans-serif" },
            new go.Binding("text", "info"))
        );

      // the FieldDraggingTool needs a template for what to show while dragging
      myDiagram.toolManager.draggingTool.fieldTemplate = fieldTemplate;

      // This template represents a whole "record".
      myDiagram.nodeTemplate =
        $(go.Node, "Auto",
          {
            movable: false,
            copyable: false,
            deletable: false,
            locationSpot: go.Spot.Center
          },
          new go.Binding("location", "loc", go.Point.parse).makeTwoWay(go.Point.stringify),
          // this rectangular shape surrounds the content of the node
          $(go.Shape,
            { fill: "#EEEEEE" }),
          // the content consists of a header and a list of items
          $(go.Panel, "Vertical",
            // this is the header for the whole node
            $(go.Panel, "Auto",
              { stretch: go.GraphObject.Horizontal },  // as wide as the whole node
              $(go.Shape,
                { fill: "#1570A6", stroke: null }),
              $(go.TextBlock,
                {
                  alignment: go.Spot.Center,
                  margin: 3,
                  stroke: "white",
                  textAlign: "center",
                  font: "bold 12pt sans-serif"
                },
                new go.Binding("text", "title"))),
            // this Panel holds a Panel for each item object in the itemArray;
            // each item Panel is defined by the itemTemplate to be a TableRow in this Table
            $(go.Panel, "Table",
              {
                name: "TABLE",
                padding: 2,
                minSize: new go.Size(100, 10),
                defaultStretch: go.GraphObject.Horizontal,
                itemTemplate: fieldTemplate
              },
              new go.Binding("itemArray", "fields")
            )  // end Table Panel of items
          )  // end Vertical Panel
        );  // end Node

      myDiagram.model =
        $(go.GraphLinksModel,
          {
            linkFromPortIdProperty: "fromPort",
            linkToPortIdProperty: "toPort",
            copiesArrays: true,
            copiesArrayObjects: true,
            nodeDataArray: [
              {
                key: 1,
                title: "Record1",
                fields: [
                  { name: "field1", info: "", color: "#F7B84B", figure: "Ellipse" },
                  { name: "field2", info: "the second one", color: "#F25022", figure: "Ellipse" },
                  { name: "fieldThree", info: "3rd", color: "#00BCF2" }
                ],
                loc: "0 0"
              },
              {
                key: 2,
                title: "Record2",
                fields: [
                  { name: "fieldA", info: "", color: "#FFB900", figure: "Diamond" }
                ],
                loc: "250 0"
              }
            ]
          });

      showModel();  // show the diagram's initial model

      function showModel() {
        document.getElementById("mySavedModel").textContent = myDiagram.model.toJson();
      }
    }
    window.addEventListener('DOMContentLoaded', init);
  </script>

<div id="sample">
  <div id="myDiagramDiv" style="border: solid 1px black; width:100%; height:300px"></div>
  <p>Drag fields between records to move them; dragging within the same node can reorder them.
     Fields can be copied when holding down the control key; they are deleted when dropped in the diagram's background.
     The "record" Nodes are not movable or copyable or deletable.</p>
  <p>The model data, automatically updated after each change or undo or redo:</p>
  <textarea id="mySavedModel" style="width:100%;height:300px"></textarea>
</div>
    </div>
    <!-- * * * * * * * * * * * * * -->
    <!--  End of GoJS sample code  -->
  </div>
</body>
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<script src="../assets/js/goSamples.js"></script>
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